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This article is from the In-Depth Report Celebrating The Nobel Prizes

Nambu, Kobayashi and Maskawa Win Physics Nobel

Work on so-called symmetry breaking helped to shape the Standard Model and explain why matter won out over antimatter



Photo by ereneta at Flickr

Three researchers in so-called broken symmetry, which helps to explain the intricate workings of the smallest constituents of the universe, were awarded the 2008 Nobel Prize in Physics today. Half the prize went to Yoichiro Nambu of the University of Chicago, with the other half shared by Makoto Kobayashi of the High Energy Accelerator Research Organization in Tsukuba, Japan, and Toshihide Maskawa of the Yukawa Institute for Theoretical Physics at Kyoto University.

All three men were rewarded for work done decades ago: Nambu for his description of “spontaneous broken symmetry” in the 1960s and Kobayashi and Maskawa for their work on symmetries and elementary particles known as quarks in the 1970s.

In 1960 Nambu described spontaneous broken symmetry, which “conceals nature’s order under an apparently jumbled surface,” according to the Nobel committee. (The committee illustrated this principle by holding up an orange—although it’s useful to describe the fruit as a sphere, it actually deviates from sphericity in subtle ways when examined up close.) Nambu’s work helps to inform the Standard Model of Particle Physics, which describes the behavior of elementary particles and three of the four fundamental forces that govern nature. (Gravity, the fourth force, has not yet found a place in the Standard Model—physicists hope that the Large Hadron Collider will help to resolve this problem once it begins operating next year.)

Specifically, Nambu’s work describes how these fundamental forces can be so different, and how elementary particles, including the particles that mediate those forces, can have such disparate masses—according to the Nobel committee, the top quark is more than 300,000 times heavier than the electron, whereas the photon has no mass at all.

“Nambu profoundly deepened our understanding of mass,” Curtis Callan of Princeton University, vice president of the American Physical Society (APS), said in an APS statement. “His prescient work of the early 60s today allows us to explain how the proton and neutron (and, by extension, the atomic nucleus) can be made of nearly massless quark constituents and yet be very massive.” (Attempts by ScientificAmerican.com to reach Nambu by phone were unsuccessful, and the answering machine at his office was full.)

Kobayashi and Maskawa, in their work, predicted the existence of three families of quarks—only two were known at the time—a prediction that was borne out in later particle accelerator experiments. This work helps to explain why all particles are not always symmetrical, including making a differentiation between particles and their antiparticles. This differentiation is critical to the universe’s existence—matter and antimatter annihilate when they come in contact, so somewhere along the line, matter must have had an edge over its counterpart to form the cosmos we inhabit today. (Both were created in equal amounts in the big bang, some 14 billion years ago.)

The two men “developed a framework for describing the intrinsic mass of quarks which has been verified in spectacular experimental detail,” Callan said in his statement. “Their work provides a framework for understanding why matter vastly dominates over antimatter in our universe." (The public relations office at Kobayashi’s institution was unavailable at press time.)

In a postconference Webcast interview, Per Carlson of the Royal Institute of Technology in Sweden said that the work of the 2008 Nobelists “allows us to understand the Standard Model of particle physics.” Said Gunnar Öquist, secretary general of the Royal Swedish Academy of Sciences, in announcing the prize, “Thanks to symmetry breaking, we sit here.”

Last year’s prize went to Albert Fert and Peter Grünberg for their discovery in the late 1980s of giant magnetoresistance, an effect that has allowed for the dramatic expansion in the capacity of hard drives.

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